1. Field of the Invention
This invention relates to an electronic timing circuit adapted to be connected between a smoke detector and its battery power supply and including a manually operable switch actuable to turn off the smoke detector for a short period when the smoke detector has triggered its alarm.
2. Description of the Prior Art
Smoke detectors are in common use in many households today. Inexpensive smoke detector which may be installed easily by the average person are commercially available. Most such smoke detectors are powered by a single 9 volt battery which is easily replaceable.
While such smoke detectors are invaluable in providing an early warning in case of fire, their sensitivity to small amounts of smoke and/or heat often causes the alarm, usually an audible signal, to be triggered by a small amount of smoke. For example, a person smoking near the detector, or the burning of toast, will both commonly cause the alarm to be sounded. The alarm will remain operative until the smoke is dissipated. Since many times the reason for sounding the alarm is not threatening, it is desirable that the annoyance of the alarm, often a harsh, piercing sound, be eliminated for the time that the alarm sounds.
Unfortunately with most smoke detectors and alarms there is no convenient way to turn them off for a brief period. Sometimes a person will disconnect the battery to eliminate the annoyance of the alarm with a real risk that the battery may not be replaced after the smoke is gone. Sometimes the smoke detector is simply disconnected, again with the risk of forgetting to reconnect it later. A simple and inexpensive device for allowing temporary disconnection of a smoke detector during false alarms and which will automatically reconnect the smoke detector is very desirable.
The present invention is an electronic timing circuit easily connected between the battery and the detection circuitry of a smoke detector. The timing circuit includes a switch which permits a person to temporarily disconnect the alarm of the smoke detector when a false alarm or malfunction occurs. Simply pressing the switch will temporarily eliminate the annoying sound of the alarm. After a preselected time delay, determined by the circuitry, the smoke detector and its alarm are reconnected automatically, eliminating the detector is reconnected, if the alarm still sounds the switch is pressed again to repeat the process.
The prior art does not provide a simple and inexpensive circuit of the type disclosed. In U.S. Pat. No. 4,404,550 to Shaw there is shown a portable smoke detector adapted to be used in luggage by travelers. The device has a switch connecting the smoke detector with its battery power supply. U.S. Pat. No. 4,525,703 to Bellino describes a portable smoke detector with a separate alarm, and an elongated electrical lead connecting the alarm to the smoke detector which, when connected, completes the circuit and permits the device to operate, and when not connected provides a conspicuous reminder that the circuit is disconnected. U.S. Pat. No. 4,567,477 to Cormier relates to a smoke detector having an alarm with an on-off switch permitting the alarm to be turned off for false alarm situations with a visually apparent indicator that the device is inoperative.
An object of the present invention is a smoke detector having an alarm which may be turned off for a short interval when the alarm sounds.
A further object of this invention is a smoke detector having an alarm which may be turned off when a false alarm sounds, but which is automatically reactivated after a short time.
Another object of this invention is a timing circuit adapted to be connected between the battery and a smoke detector, and including a switch for temporarily disconnecting the smoke detector.
A still further object of this invention is an inexpensive circuit adapted to be attached easily to a smoke detector which may be actuated to turn off the detector and its alarm for a brief period.